2003 Park Avenue Rear End Thud, Clunk, Thump Over Bumps ... Help!!!

[Zeke27]

Hello,
Thanks for reading my post. Whenever I drive over bumps (small & large), I hear a distinct thud or clunk or thump in the rear passenger side of my 2003 Park Avenue. I just replaced both air shocks and the sway bar bushings. Nothing is loose in the trunk and the spare tire assembly is tightly secured. My mechanic checked all the other parts of the rear suspension and tightened all available bolts but this noise persists. It's driving me crazy! I just bought the car and it drives beautifully. On a smooth stretch of road there is no thud sound at all, but when I go over a bump, it's clearly audible. This clunking noise occurs milliseconds after I hear the sound of the rear wheel, shock and spring handling the bump. The noise is the last sound I hear and it is just as loud. Has this happened to any other Park Avenue owners? If so, please help if you can. I simply cannot afford to take my car to a Buick/GM dealer.

 

[bigsky]

Whenever I drive over bumps (small & large), I hear a distinct thud or clunk or thump in the rear passenger side of my 2003 Park Avenue. I just replaced both air shocks and the sway bar bushings.

I can offer my experience... When I replaced the rear air shocks on a 2K base PA with the KYB, I kept getting the thump over bumps. Even tried another new pair of the same but still the noise. The mounts were replaced with aftermarket. Sway bar bushings a couple of times.

Did some research, some thought the rear mounts were critical and ACDelco mounts should be used. Replaced with ACDelco rear shocks & mounts and the thud was gone.

Looking back, I am wondering if the rear height just needed to be raised a bit? There is an adjustment on the rear height sensor. I wonder because some have had a similar thump experience with the Gabriel rear shocks, yet both the KYB & Gabriel work fine for others. BTW I prefer the KYB for the front, and was looking forward to using the KYB in the rear.

Before doing anything else...I would adjust the rear height sensor to add a little more height to the rear. Also, take a look at the rear ride height and note if it looks to be sagging.

 

[Zeke27]

Thank you, bigsky. Before I read your reply, I had ordered a set of new aftermarket rear shock mounts ($25). I'm going to have them installed and see if that helps. I will also ask my mechanic to adjust the rear height sensor. When the car was last on the hoist, I noticed that the frame is hollow. Could something have come loose inside the hollow frame? When driving normally, this possible object would just sit inside the frame and not move. But when the car goes over ripples and bumps, the object would be jarred loose and bounce around. I know, I'm probably really reaching here but this clunking noise is very troubling. What made me think of this idea was, when I was a kid, my Dad had a big Pontiac and somehow, a golf ball found its way into the gas tank. Sure enough, whenever we went over bumps, the damn thing would clunk around inside the old metal gas tank. The thing I remember most about this incident was my Dad pointing out that the major clunk came after the suspension handled the bump. The clunk was the last noise we heard. It's the same thing with this clunk. It's the last noise I hear. Finally, it drove my Mom nuts, so my Dad had it removed! Any other possibilities?

 

[Irish]

I gave my son my 2005 Lesabre with 330,000 miles on it when he got out of college. He brought it home one weekend and told me the spare tire was loose in the trunk and clunked whenever he went over a bump. I opened the trunk and saw that he had wedged pieces of 2x4 around the spare tire. I was able to recreate the noise bouncing the back end of the car with the spare tire in or removed from the trunk. His problem was a bad upper shock mount on 1 side and a blown shock on the other side. The top of the shock was pushing right through the shock mount and making the clunking noise. New shocks and upper mounts and it went down the road quiet again.